It really is...I must admit, I laughed out loud at almost every image in this thread. XD Maybe I personally am just incapable of feeling threatened by these kinds of character designs...
Also, I feel like 'evil smiley face' doesn't really work with this character in particular, because one of the most important aspects of his character concept is that, unlike other fantasy gods/dark magical girl mascots, he is NOT evil. He has his moments, but he's not a malicious entity; he should never look like he might be looking forward to hurting someone. Portraying him with a giant maniacal smile would send the wrong message.
Oddly enough, I feel like the answer might be something like this? Like, maybe the way to make him intimidating is to actually leave behind the simplistic circular shape language and suddenly make him look like A Person.
It gave me the idea to make him a stipple silhouette of a human being, like:

...I think if I could make this look a tad more realistic (maybe use an actual photo as a base) this could be it. ^^